Electromagnetic prime movers



March 27, 1956 s oc ETAL ELECTROMAGNETIC PRIME MOVERS Filed May 12. 19534 Egg? 6 134 E I- zrd/ I Ill United States Patent O 2,740,057ELECTROMAGNETIC PRIME MOVERS Friedrich Blurnenstock, Stuttgart, andErnst Hiiberle, Stuttgart-Varhingen, Germany, assignors to Robert BoschG. m. b. H., Stuttgart, Germany Application May 12, 1953, Serial No.354,572 Claims priority, application Germany May 13, 1952 10 Claims.(Cl. 31029) The invention relates to a double-barreled armature magneticprime mover, which is particularly suitable for the driving ofhair-cutting machines and the like.

Such electromagnetic drives usually consist of a magnet core providedwith two exciter coils, at least substantially E-shaped, and anoscillating lever which is alternatively attracted by the two outer armsand in doing so rolls on a preferably slightly curved track above themiddle arm of the magnet core. This rolling motion is effected, in thecase of most arrangements of this kind, against the force or" at leastone spring engaging on the oscillatmg lever and which tends to press thebarrel armature against its rolling track and to keep it in its middleposition or to return it thereto.

A difficulty in such arrangements is that the oscillating lever, if nouseful output is taken off from it, may rise from the rolling track andconsequently flap and produce a loud disturbing noise, by reason of itstaking up a large amplitude of movement. On the other hand, however, amounting engaging in the middle of the roller track and armature mustleave so much play that the centre point of the armature can, inswinging backwards and forwards, move sufficiently far towards the outerarm and, in the second component of the movement, remove itselfsufiiciently far from the centre point of the roller track.

According to the invention this disadvantage is avoided in that thearmature is elastically secured to the iron core by the use of rubber asan intermediate layer.

The invention is further described with reference to the accompanyingdrawings showing various forms of construction by way of example.

in the drawings:

Fig. 1 shows an electric hair cutting machine with a double barreledarmature magnet prime mover in longitudinal section, and

Fig. 2 a cross section on the line II-II of Fig. 1,

Fig. 3 the armature mounting as shown in Figv 2 in partial section on anenlarged scale;

Figs. 4, 5 and 6 show two other types of mounting, likewise on anenlarged scale.

The drive of the hair cutting machines illustrated in Figs. 1 to 3 isaccommodated in two halves of a handle 11 and 12 manufactured of plasticmaterial, and consists substantially of a U-shaped iron core 13, alaminated swinging arm 14 and a driving arm 15 bent at right angles andsecured to this armature, which can be engaged with a cutter head (notshown). On the outer arms 17 and 18 of the magnetic coil excitationcoils 20and 21 are mounted constructed with the same number of windingswhich magnetise the free ends of the outer arms always opposed to eachother after being connected to alternating current mains and on theoperation of a toggle switch 22.

The permanent magnet 24 extends through the two outer arms 17 and 18,when the armature 14 is in the middle position shown in Fig. 1,symmetrically with a magnetic direct flow, as indicated by arrows inFig. l. The alternating flow produced by the operating current in theexcitation coils superimposes itself on this direct flow. By suitablechoice of the number of windings for the excitation coils 20 and 21, theamplitude of the alternating flow is so adjusted to the most favourableworking point that it lies within the extent of the direct flow. Duringthe time when the alternating flow reaches its highest value, themagnetic force adds up in an outer arm to about twice the value, whilstin the other arm alternating flow and direct flow compensate each otherand the armature 14 is moved with a tensile force corresponding to twicethe value of the direct flow towards the more powerfully magnetisedouter arm. The armature 14 in this process rolls on the face of the poletube 19 constructed as a roller track 25 slightly curved with a largeradius R. On reversing the excitation current during the followingsemiwave the other outer arm reaches twice the magnetic power, so thatan opposite swinging movement is imposed on the armature and the middlesection of the armature rolls towards this arm over the arcuate track25.

A doubly curved leaf spring 26 clipped between the armature 14 and thewall of the casing 11, 12, tends to press the armature against theroller track 25 keeping it in its middle position or returning itthereto. Two helical springs 23 and 27 inserted into the outer arms 17and 18 are used for limiting the pivotal motion of the armature 14.

For mounting the armature, the transverse shaft M of which movesaccording to an epicycloid path upon its swinging movement, two brassrods 28 and 29 are used which are mounted on the middle arms of themagnet frame with rivets 30 and 31 passing through, and bores 32 and 33on their ends projecting above the pole shoe 19 are used for sealing abearing bolt 35 disposed in the transverse shaft M of the armature. Tworubber discs 36 and 37 disposed on the bearing bolt in the directvicinity of the armature plates are tensioned in the bores 32 and 33 ofthe brass rods 28 and 29 and permit the necessary deflection of thebearing pin upon the pivotal motion of the armature. The rubber discs 36and 37 are gripped on both sides of the brass rods 28 and 29 from theoutside with large discs 38 and 39 slipped loosely on the bolt 35 andare tensioned against the armature by a disc each, 40 and 41, riveted tothe ends of the bearing bolt 35.

During the pivotal movement of the armature, the bearing bolt 35 can,therefore, move inside the bores 32 and 33 to the necessary extent, asthe rubber discs 36 and 37 give elastically to such an extent and actsimultaneously as noise dampers. Therefore, the bearing bolt 35 and therubber discs 36 and 37 form a bearing made of inherently resilientmaterial. By the term inherently resilient material it is meant toindicate that the material has a natural resiliency which is due to thematerial itsclr" and not to any particular shape in which the materialmay be formed. The mounting of the armature as shown in Fig. 4 ditiersof that as described above by the feature that the armature 54 has alarger bore 55 into which the bearing pin 57 being covered with a smallrubber tube 56 is glued or cemented; the ends of the rubber tube 56projecting at both sides of the armature are inserted into the bosses 58arranged at the ends of the brass rods 59.

Another modification needing somewhat more space is shown in Figs. 5 and6. The armature 64 of this modification is provided with a notch 65parallel to the cross axis of the armature, into this notch a piece ofround rubber is inserted which rests in a similar notch of an abutment67. it is possible to simplify this construction by using the wall ofthe housing as abutment, the housing wall being provided with a notch.

We claim:

1. In a hair cutting machine, in combination, a housing unit; anelectromagnetic core unit arranged within said 3 housing unit, one ofsaid units having a guide face; an elongated armature having a portionwith a face thereof superimposed on said guide face, at least one ofsaid faces being curved so that said elongated armature is adapted tocarry out an oscillatory rolling movement on said guide face; and abearing element consisting of inherently resilient material andinterposed between another face of said portion of said elongatedarmature and one of said units and supporting said portion of saidelongated armature for damped movement in directions required duringoscillatory rolling movement of said armature on said guide face.

2. In a hair cutting machine, in combination, a housing member; anE-shaped magnetic core member arranged within said housing member, thecenter leg of said core member having a curved end face; an elongatedarmature having a central portion with a face thereof superimposed onsaid curved end face of said central leg of said core member so as to beadapted to carry out an oscillatory rolling movement on said curved endface; and a bearing element interposed between another face of saidcentral portion of said elongated armature and one of said members, saidbearing element consisting of inherently resilient material supportingsaid central portion of said elongated armature for damped movement indirections required during oscillation of said armature on said curvedend face of said center leg.

3. In a hair cutting machine, in combination, a housing member; anE-shaped magnetic core member arranged within said housing member, thecenter leg of said core member having an end face; an elongated armaturehaving a central portion with a face thereof superimposed on said endface of said central leg of said core member, at least one of said facesbeing curved so that said elongated armature is adapted to carry out anoscillatory rolling movement on said end face of said center leg of saidcore member; and a bearing element interposed between another face ofsaid central portion of said elongated armature and one of said members,said bearing element consisting of inherently resilient materialsupporting said central portion of said elongated armature for dampedmovement in directions required during oscillation of said armature onsaid end face of said center leg.

4. In a hair cutting machine, in combination, a housing unit; anelectromagnetic core unit arranged within said housing unit and having aguide face; an elongated armature having a portion with a face thereofsuperimposed on said guide face of the said electromagnetic core unit,at least one of said faces being curved so that said elongated armatureis adapted to carry out an oscillatory rolling movement on said guideface; and a bearing element consisting of inherently resilient materialand interposed between another face of said portion of said elongatedarmature and one of said units and supporting said portion of saidelongated armature for damped movement in directions required duringoscillatory rolling movement of said armature on said guide face.

5. In a hair cutting machine, in combination, a housing member; anE-shaped magnetic core member arranged within said housing member, thecenter leg of said core member being made of a permanent magneticmaterial and having a curved end face; an elongated armature having acentral portion with a face thereof superimposed on said curved end faceof said central leg of said core member so as to be adapted to carry outan oscillatory rolling movement on said curved end face; a pair ofsolenoid coils each wound on one outer leg of said magnetic core member;means for simultaneously supplying an A. C. voltage to said solenoidcoils; and a bearing element interposed between another face of saidcentral portion of said elongated armature and one of said members, saidbearing element consisting of resilient material supporting said centralportion of said elongated armature for damped movement in directionsrequired'during oscillation of said armature on said curved end face ofsaid center leg.

6. In a hair cutting machine, in combination, a housing member; anE-shaped magnetic core member arranged within said housing member,-thecenter leg of said core member being made of a permanent magneticmaterial and having a curved end face; and elongated armature having acentral portion with a face thereof superimposed on said curved end faceof said central leg of said core member so as to be adapted to carry outan oscillatory rolling movement on said curved end face; means forresiliently urging the end portions of said armature away from the outerlegs of said magnetic core member; a spring urging said armature awayfrom the Wall of said housing member; a pair of solenoid coils eachwound on one outer leg of said magnetic core member; means forsimultaneously supplying an A. C. voltage to said solenoid coils; and abearing element interposed between another face of said central portionof said elongated armature and one of said members, said bearing elementconsisting of resilient material supporting said central portion of saidelongated armature for damped movement in directions required duringoscillation of said armature on .said curved end face of said centerleg.

7. Apparatus as claimed in claim 2 wherein said bearing element includesrubber discs mounted between said central portion of said elongatedarmature and said center leg of said magnetic core member.

8. Apparatus as claimed in claim 2 wherein said bearing element includesa rubber tubular member interposed between said central portion of saidelongated armature and said central leg of said magnetic core member.

9. Apparatus as claimed in claim 1 wherein said bearing element includesa rubber rod member and is interposed between the central portion ofsaid elongated armature and said housing unit.

10. In a hair cutting machine, in combination, a housing unit; anelectromagnetic core unit arranged within said housing unit, one of saidunits having a guide face; an elongated armature having a portion with aface thereof superimposed on said guide face, at least one of said facesbeing curved so that said elongated armature is adapted to carry out anoscillatory rolling movement on said guide face; a resilient bearingelement interposed between another face of said portion of saidelongated armature and one of said units and supporting said portion ofsaid elongated armature for damped movement in directions requiredduring oscillatory rolling movement of said armature on said guide face;and additional resilient means permanently urging said superimposed faceof said elongated armature into contact with said guide face.

References Cited in the file of this patent UNITED STATES PATENTS2,149,126 Spencer Feb. 28, 1939 2,438,958 Abrahamson Apr. 6, 19482,516,718 Oriol July 25, 1950 FOREIGN PATENTS 259,232 Switzerland June1, 1949

